Managing this array of crops, as well as 180 workers, is a task in itself. But ask Sou what’s the most troublesome problem for his 26-year-old business. He’ll reply with two words that all local farmers’ would love to swat out of their vocabulary. “The fruit fly is the No. 1 inhibitive problem for Hawaii agriculture,” Sou says. “It stunts a lot of the potential Hawaii has to export crops.”

These days, Sou and dozens of other Hawaii farmers have enjoyed some respite from the pest. The Hawaii Area Wide Fruit Fly Integrated Pest Management Program (HAW-FLYPM) began three years ago on Oahu, Maui and the Big Island, with the help of a $5 million federal grant. The five-year program partners the U.S. Department of Agriculture, the state Agriculture Department and the University of Hawaii.

HAW-FLYPM doesn’t focus on eradicating the fruit fly, a feat supposedly accomplished in countries like Okinawa and Guatemala. That’s unfeasible here, experts say, because of the high costs — potentially billions of dollars — and ecological issues. Instead, HAW-FLYPM aims to reduce the fruit fly population to manageable levels for farmers and backyard growers.

Hawaii is the only state under federal fruit fly quarantine. For more than 50 years, the quarantine has blocked exports to the Mainland of most Hawaii-grown fruits and vegetables susceptible to infestation. Certain vulnerable fruits — such as papayas, avocados and bananas — can be cleared for export if they undergo USDA-approved post-harvest treatments (i.e. irradiation and treatment with extreme hot or cold temperatures).

“I don’t want to give the impression that every fruit is infested; the USDA set up these requirements to prevent the odd infestation,” says Eric Jang, research leader for the Tropical Plant Pests Research Unit at the USDA’s Pacific Basin Agricultural Research Center. “The quarantine protects the Mainland. If one got by the system, the impact would be devastating to California’s agriculture industry, which is huge.”

It’s tough to measure the economic impact of the pest on Hawaii’s $1.94 billion agriculture industry. That’s because the fruit fly inflicts the most damage to the industry’s potential. “Crops that are vulnerable to infestation are generally not grown, since it makes no sense to grow crops with lousy yield,” says Lyle Wong, administrator of the plant industry division at the state Department of Agriculture. That’s also why fruits that aren’t susceptible to infestation, such as pineapple and macadamia nut, have emerged as Hawaii’s export staples.

HAW-FLYPM uses a combination of methods to suppress fruit fly populations: bagging or burying rotting fruit, which are ideal breeding locations for fruit flies; spraying a protein-based insecticide that is less toxic than ordinary sprays; and using chemical attractants to lure flies into retrievable traps.

The program also employs biological control methods, such as releasing the fruit fly’s natural enemy, the parasitoid, into the environment. HAW-FLYPM also rears millions of infertile male fruit flies and releases them into the wild. “Because there is no offspring, the population is reduced through a series of sterile matings,” Jang says.

Alec Sou began participating in the program in March 2002. Since then, he has noted a drop in his farms’ fruit fly population. Monitoring stations are set up at various intervals around his property. During the peak population months of August and September, Sou used to see up to 200 flies per station. This past year, he recorded readings of less than one fly per station.

While Hawaii farmers’ long-fought battle against the fruit fly is far from over, Sou is satisfied with the results he sees today. “The quality, consistency and quality of my crops have improved,” Sou says. “In some crops, we’ve seen a double in the yield, particularly the melons. These results are measurable.”